STMicroelectronics 1.2 W fully differential audio power amplifier DEMOTS4995J DEMOTS4995J Fiche De Données
Codes de produits
DEMOTS4995J
TS4995
Application information
19/26
Therefore, the power dissipated by each amplifier is:
P
diss
= P
supply
- P
out
(W)
and the maximum value is obtained when:
and its value is:
Equation 3
Note:
This maximum value is only dependent on the power supply voltage and load values.
The efficiency is the ratio between the output power and the power supply:
Equation 4
The maximum theoretical value is reached when V
peak
= V
CC
, so:
The maximum die temperature allowable for the TS4995 is 125° C. However, in case of
overheating, a thermal shutdown set to 150° C, puts the TS4995 in standby until the
temperature of the die is reduced by about 5° C.
overheating, a thermal shutdown set to 150° C, puts the TS4995 in standby until the
temperature of the die is reduced by about 5° C.
To calculate the maximum ambient temperature T
amb
allowable, you need to know:
●
The power supply voltage, V
CC
●
The load resistor value, R
L
●
The package type, R
thja
Example: V
CC
=5 V, R
L
=8
Ω,
R
thja-flipchip
= 100° C/W (100 mm
2
copper heatsink).
, this gives a result of:
P
dissmax
= 633mW
T
amb
is calculated as follows:
Equation 5
Therefore, the maximum allowable value for T
amb
is:
T
amb
= 125-100x0.633=61.7° C
P
diss
2 2V
CC
π
R
L
----------------------
P
out
P
out
–
=
∂
Pdiss
∂
P
out
---------------------
= 0
)
W
(
R
Vcc
2
max
Pdiss
L
2
2
π
=
η
=
P
out
P
supply
-------------------
=
π
V
peak
4V
CC
--------------------
η
=
π
4
----- = 78.5%
T
amb
125
°
C
R
thja
P
dissmax
×
–
=